Modern metal working and forming processes normally require the use of cutting and grinding fluids whose function is to facilitate machining operations by cooling and lubricating the workpiece. In machining operations where only lubrication is necessary. lube oils are generally used. When lubrication and cooling are required, lube oil-in-water emulsions are generally used. The cooling function is accomplished by the ability of the fluid to carry off heat generated by frictional contact between the tool and the workpiece. Cooling aids tool life, preserves tool hardness and helps to maintain the dimensions of the machined parts. Cutting and grinding fluids also serve to carry away debris from the work area. With respect to straight lube oils and lube oil-in-water emulsions, they both conventionally contain additives such as stabilizers, biocides, defoamants, corrosion inhibitors, extreme pressure active materials, metal cleaners, and the like.
Over the years, developments with respect to cutting and grinding fluids (collectively referred to herein as machining fluids) have been numerous. Machining fluid technology has expanded to include the formulation and use of mineral, vegetable, and fatty oils to impart an extended range of desirable properties--corrosion protection, resistance to bacterial attack, improved lubricity, greater chemical stability, improved emulsibility, and the like. In more recent years, water-soluble fluids and fluids comprised of chemicals in water solution have replaced many traditional oil-based fluids in many different applications. This trend has been spurred by, among other things, dwindling oil supplies and rising costs for petroleum products. Increased costs to clean workpieces and rising costs of machining fluid disposal have also fueled development and use of synthetic water-based fluids.
Increasingly significant in the formulation of machining fluids is a confusing array of government regulations (federal, state, and local) pertaining to solvent emissions and waste disposal. The composition and use of machining fluids is now more than ever directly impacted by human safety considerations, air and water pollution regulations, chemical toxicity registration, waste disposal regulations, shipping regulations, energy policy, et cetera. The machining fluid selection process is further complicated by the fact that the machining fluid is only one component in an integrated metal-fabrication system.
Significantly, chlorofluorocarbons (CFCs), generally formulated with a lubricant, have for the last 30 years also been used in various machining operations.
Advantages of CFC solvent-based fluids over traditional oils and water/lubricant blends include their non-flammability and cleanliness. In general, CFC solvents evaporate completely and rapidly, thereby limiting the area of runoff and lubricant deposition.
Additionally, using CFC-based fluids on large parts with difficult-to-reach areas having stringent cleanliness requirements, such as aircraft wings, generally saves many man-hours of cleaning time. CFC-based fluids are also nonflammable, another desirable characteristic in work areas where heat and sparks may be generated.
Currently, there is a need to find replacements for CFC-based machining fluids, they are no longer being manufactured because of the Montreal Protocol and its attendant amendments which limit the use and production of certain ozone depleting chemicals. Thus, environmental concerns require that replacement machining fluids have low ozone depletion potentials, low global warming potentials, and short atmospheric lives; whereas workplace and machining concerns require that they have low toxicities, high flashpoints (or be non-flammable), non-corrosive characteristics towards a variety of metals, high heat-of-vaporization values (able to remove heat quickly), and are be able to dissolve (or otherwise disperse a lubricant) and evaporate quickly so as to leave behind little or no non-volatile residue (NVR).
Although significant progress has been made with respect to machining fluid formulations, there is still a need in the art for improved machining fluid formulations that further alleviate environmental and worker safety concerns, especially within the context of finding a replacement machining fluid for CFC-based solvents. The present invention fulfills these needs and provides for further related advantages.